This invention relates to a valve protector for a compressed gas cylinder, and more particularly to a rotatable valve protector which is readily secured to a compressed gas container and easily removable therefrom.
Metal-walled cylinders are widely employed for containing gas under pressure, and such cylinders are commonly provided at one end with a neck on which is mounted a valve or other instrumentality to effect controlled release of the contained gas. Merely by way of example, cylinders of this type are used to hold industrial and welding gases, as well as gaseous carbon dioxide for the carbonation of beverages.
Because of their smooth, elongated shape and considerable weight of approximately 140 lbs., such cylinders are inconvenient to handle. Moreover, the exposed, projecting valve on such cylinders is vulnerable to misadjustment or damage, either by impacts with objects or hard surfaces incident to the handling of the cylinder, or by blow from moving objects when the cylinder is stationary. An even more important consideration than damage from moving objects is the cylinder tipping over, which will cause the valve to shear off.
Accordingly, it has heretofore been proposed to provide a protecting structure mounted on the neck of the cylinder adjacent to the valve, to shield the valve from impacts and blows to which the valve would otherwise be subjected. One widely used valve protecting structure is a cap threadedly mounted on a cylinder neck ring and almost completely enclosing the valve. Since the cap must be removed before a regulator and hose or other attachment can be connected to the valve, it does not protect the valve during the use of the cylinder. Moreover, in addition to being inconvenient, the necessity of removing the cap results in a high rate of loss of such caps with the attendant undesirable expense for replacement. Furthermore, when the cylinder is being transported by tipping and rolling it, the use of the conventional cap requires that the operator continually tighten the cap as the cylinder is being rolled in order to prevent the cap from unscrewing due to the clockwise rotation of the cylinder and the consequent counter-clockwise rotation of the cap, if it is held stationary relative to the threads of the neck ring.
It has alternately been proposed to provide a protecting structure which is rotatably mounted on the cylinder neck and has one or more openings, both to enable access to the shielded valve and to adapt the protecting structure for use as a handle in carrying the cylinder. Since the valve customarily has a fitting that projects on one side for connection to a hose, regulator, or other attachment, and a hand wheel positioned at its outer extremity, a lateral access opening is provided in the protecting structure to enable connection of the regulator and hose or other attachment to the fitting, while the hand wheel is accessible through an enlarged end opening of the protecting structure.
Such an earlier proposed construction is disclosed in U.S. Pat. No. 3,006,360, issued on Oct. 31, 1961 to P. R. Oxenham. Although the Oxenham protecting structure is rotatably mounted on the neck of the cylinder, it has inherent disadvantages. Because it has a threaded locking collar which terminates well above the upper surface of the cylinder and because the area of the protecting structure in contact with the outer surface of the locking collar is so narrow, a ring must be welded to the collar to prevent the contacting portion of the protecting structure from sliding down below the collar and into engagement with the top of the cylinder. Moreover, the ring can only be welded on its lower side, which means that the welding process is costly and inefficient and that the attachment of the ring to the collar is intrinsically weak.
Furthermore, the narrow area of contact between the protecting element and the outer surface of the threaded collar makes the Oxenham protecting structure vulnerable to binding when an attempt is made to rotate it relative to the cylinder under any significant load. In addition, the thinness of the contacting portion of the protecting structure renders it susceptible to bending when subjected to substantial loads.
Moreover, the threaded locking collar of the Oxenham device is prevented from unthreading rotation merely by the interference of starting revolutions of thread on the locking collar with the starting revolutions of thread around the cylinder neck ring. Thus, the rotation of the protecting structure around the locking collar and the tendency of the protecting structure to bind with the locking collar can cause unthreading rotation of the locking collar on the threads around the cylinder neck and resultant loosening of the entire protecting device.